Liquid crystal display input/output device

ABSTRACT

The present invention provides a liquid crystal display device including a pair of electrode substrates and a display medium sandwiched between the electrode substrates and including a polymeric wall and liquid crystal regions at least partly surrounded by the polymeric wall. In this liquid crystal display device, the polymeric wall is tightly attached to both the electrode substrates. Furthermore, the invention also provides a method for producing a liquid crystal display device including a pair of electrode substrates, at least one of which is transparent, and a display medium including a polymeric wall and liquid crystal regions at least partly surrounded by the polymeric wall and sandwiched between the electrode substrates. This method includes the steps of injecting a mixture including liquid crystal and a photopolymerizable material between the electrode substrates; and irradiating the mixture with light having light intensity distribution so as to cause phase-separation between the liquid crystal and the photopolymerizable material, thereby forming the liquid crystal regions in weakly irradiated areas.

This is a divisional of application Ser. No. 08/324,976 filed on Oct.18, 1994 which is a continuation-in-part of commonly-owned U.S.application Ser. No. 08/054,454, YAMADA et al, filed Apr. 27, 1993 nowU.S. Pat. No. 5,473,450.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device, inwhich a display medium including liquid crystal regions surrounded by apolymeric wall and sandwiched between a pair of opposing substrates,applicable to a plane display device such as a personal computer, aliquid crystal television set, a portable display including a filmsubstrate, and a display apparatus in which a display portion and aninput portion are integrated for adopting a pen entry operation.

2. Description of the Related Art

Conventional liquid crystal display devices utilize a variety of displaymodes as follows: As liquid crystal display devices utilizing anelectrooptic effect, a twisted nematic (TN) liquid crystal displaydevice and a super-twisted nematic (STN) liquid crystal display deviceusing nematic liquid crystal have been put to practical use (JapaneseLaid-Open Patent Publication No. 59-119320). Further, as an STN liquidcrystal display device achieving a brighter display, a reflective typeliquid crystal display device including one polarizing plate is proposed(Japanese Laid-Open Patent Publication Nos. 4-97121 and 4-289818).

As liquid crystal display devices utilizing light scattering of liquidcrystal without using a polarizing plate, those utilizing a dynamicscattering (DS) effect and a phase change (PC) effect have beenproposed.

Recently, as a liquid crystal display device requiring neither apolarizing plate nor an alignment treatment, a display device utilizingthe birefringence of liquid crystal so as to electrically control thetransparent state and the opaque state has been proposed. In such aliquid crystal display device, the refractive index of the liquidcrystal molecule with respect to ordinary light is basically matchedwith the refractive index of a polymeric material supporting the liquidcrystal. As a result, the transparent state is displayed when a voltageis applied to uniformly orient the liquid crystal molecules, and theopaque state Is displayed under application of no voltage because oflight scattering caused by the turbulence of the liquid crystalmolecules. It is disclosed that such a liquid crystal display device isproduced by using a mixture of a photosensitive or thermosettingmaterial and liquid crystal, from which the photosensitive orthermosetting material alone is deposited by polymerization, therebyforming a liquid crystal droplet surrounded by the polymeric material(resin) (Japanese National Publication No. 61-502128).

As another type of a liquid crystal display device, a non-scatteringtype liquid crystal device having viewing angle characteristics improvedby using a polarizing plate, is also proposed (Japanese Laid-Open PatentPublication No. 5-27242). This liquid crystal display device is producedby causing phase-separation in a mixture of liquid crystal and aphotopolymerizable material to obtain a complex material for liquidcrystal domain and a polymeric wall. The thus formed polymeric wallcauses random alignment of the resultant liquid crystal domains, andhence, the liquid crystal molecules in the respective liquid crystaldomains rise in different directions. As a result, the apparentrefractive index is constant when seen from any direction, and thus, theviewing angle characteristics at halftone are improved.

As a similar liquid crystal display device, the Applicant has proposedthe following device (Japanese Patent Application No. 4-286487): Inproducing this liquid crystal display device, light control means suchas a photomask is used in light irradiation to cause photopolymerizationin a mixture of liquid crystal, a photopolymerizable material and thelike, thereby forming liquid crystal domains omnidirectionally, i.e.,radially, oriented in a pixel region. Accordingly, the liquid crystalmolecules are moved in such a manner that an umbrella is opened orclosed by controlling a voltage to be applied. This liquid crystaldisplay device has further improved viewing angle characteristics.

In the liquid crystal region in the abovementioned conventional liquidcrystal display device, the liquid crystal is aligned by using analignment regulating force on a substrate. Since the polymeric wall isan isotropic phase, however, its color is different from that of theliquid crystal region, resulting in decreasing the brightness indisplaying white. This problem is particularly severe in the reflectivetype liquid crystal display device for the following reason: When thereflective type liquid crystal display device includes a non-pixelportion formed from a material of the isotropic phase, the isotropicphase between the polarizing plates is in the similar state as that fordisplaying black. Therefore, the display obtained by such a reflectivetype liquid crystal display device is generally dark.

Japanese Laid-Open Patent Publication No. 4-323616 discloses a methodfor producing a liquid crystal display device in which partitions arepreviously formed on a substrate to be used for manufacturing a cell andliquid crystal is injected into the cell. In this production method,however, the alignment direction between the partition and the liquidcrystal is different from the alignment direction by an alignment filmon the substrate. Therefore, the alignment direction of the liquidcrystal is disordered in the vicinity of the partition, resulting indecreasing the contrast. Moreover, since the partitions are formed onthe substrate and then a counter substrate is attached to the substrate,there is no material between the substrates to attach them to eachother, resulting in decreasing the physical strength of the cell.Furthermore, since an alignment treatment is conducted on the alignmentfilm on the substrate before forming the partition on the substrate byphotolithography or the like, the alignment regulating force on thesubstrate is weaken, and hence it is impossible to obtain excellentdisplay characteristics. In addition, it is difficult to adjust theheight (in the direction vertical to the surfaces of the substrates) ofthe partitions on the substrate, and a spacer is additionally used toobtain the desired thickness of the cell. Therefore, the thickness ofthe cell is varied depending upon whether or not the spacer ispositioned on the partition, resulting in difficulty in controlling thethickness of the cell accurately.

In such a conventional liquid crystal device, the thickness of a liquidcrystal layer, i.e., the so-called cell thickness, is varied with easeby an external pressure. Therefore, when the liquid crystal displaydevice adopts a pen entry operation, the pen entry causes local displayirregularity. Therefore, in order to avoid this irregularity, it isnecessary to provide a protection film (a protection substrate) or thelike over the liquid crystal display device. The use of the protectionfilm or the like leads to a larger distance between the display portionand the pen entry portion, and this distance causes a parallax, causinga difficulty in the operation.

In a liquid crystal display device having improved wide viewing anglecharacteristics, a sufficient duty ratio cannot be obtained because ofthe lack of the sharpness in the electro-optical characteristics.Therefore, it is necessary to use an expensive thin film transistor(TFT), resulting in a high production cost.

SUMMARY OF THE INVENTION

The liquid crystal display device of this invention comprises a pair ofelectrode substrates; and a display medium sandwiched between theelectrode substrates and including a polymeric wall and liquid crystalregions at least partly surrounded by the polymeric wall. In thisdevice, the polymeric wall is tightly attached to both the electrodesubstrates.

In one embodiment, a material to be used for forming the polymeric wallincludes polymeric liquid crystal.

In one embodiment, liquid crystal contained in the liquid crystalregions is nematic liquid crystal having a positive dielectric constantanisotropy and including a material having an optical activity, and anangle between alignment directions in the liquid crystal regions in avicinity of the respective electrode substrates is 220° or more and 290°or less.

In one embodiment, one of the electrode substrates is provided with apolarizer on an outer surface thereof not facing the display medium, theother electrode substrate is provided with a reflecting plate, and theelectrode substrate between the display medium and the polarizer has aretardation film.

In one embodiment, the liquid crystal regions have a retardation of 500nm through 800 nm.

In one embodiment, the electrode substrate having the retardation filmhas a retardation of 150 nm through 380 nm.

In one embodiment, the liquid crystal display device further comprises acolor filter.

In one embodiment, one of the electrode substrates has a film with areflecting function, and at least part of the film transmits light.

In one embodiment, the liquid crystal regions have a smectic phase and anematic phase.

This invention also provides a method for producing a liquid crystaldisplay device including a pair of electrode substrates, at least one ofwhich is transparent, and a display medium including a polymeric walland liquid crystal regions at least partly surrounded by the polymericwall and sandwiched between the electrode substrates. This methodcomprises the steps of injecting a mixture including liquid crystal anda photopolymerizable material between the electrode substrates; andirradiating the mixture with light having a light intensity distributionso as to cause phase-separation between the liquid crystal and thephotopolymerizable material, thereby forming the liquid crystal regionsin weakly irradiated areas.

In one embodiment, the light intensity distribution is provided by usinga photomask.

In one embodiment, the mixture is photopolymerized when the liquidcrystal is in one of states of an isotropic phase and a nematic phase,and then, the liquid crystal is allowed to be in one of states of asmectic phase and the nematic phase, while causing photopolymerizationin the mixture again.

In one embodiment, the step of injecting the mixture is conducted whenthe liquid crystal is in one of states of an isotropic phase and anematic phase, and the substrates including the mixture is heated toattain the isotropic phase of the liquid crystal, and then cooled toattain the nematic phase of the liquid crystal before the step ofirradiating the mixture.

In one embodiment, light with a wavelength of 350 nm or more is used inthe step of irradiating the mixture.

Alternatively, the liquid crystal display device of this inventioncomprises liquid crystal regions that are formed between a pair ofelectrode substrates and at least partly surrounded by a polymeric wallformed in a pattern. In this device, the liquid crystal regions and thepolymeric wall are aligned in accordance with an alignment regulatingforce on the electrode substrates under application of no voltage.

In one embodiment, the polymeric wall and the liquid crystal regionsinclude a chiral agent.

In one embodiment, a chiral pitch P_(P) of the polymeric wall and achiral pitch P_(LC) of the liquid crystal regions satisfy the followingrelationship:

    P.sub.P <10×P.sub.LC

In one embodiment, refractive index anisotropy Δn_(P) of the polymericwall and refractive index anisotropy Δn_(LC) of the liquid crystalregions satisfy the following relationship:

    Δn.sub.P >(1/10)×Δn.sub.LC

In one embodiment, the liquid crystal display device further comprisesan optical portion formed in a pattern on an inner surface of one of theelectrode substrates. The optical portion has a light transmission of50% or less with regard to light having a wavelength of 250 nm or moreand 400 nm or less, and transmits at least 20% or more of light with awavelength exceeding 400 nm having a maximum value in the lighttransmission.

Alternatively, the invention provides a method for producing a liquidcrystal display device including a pair of electrode substrates at leastone of which is transparent, a polymeric wall formed in a patternbetween the electrode substrates and liquid crystal regions at leastpartly surrounded by the polymeric wall. The method comprises the stepsof injecting a mixture between the electrodes, the mixture including atleast liquid crystal, photopolymerizable liquid crystal including apolymerizable functional group in its molecule and a chiral agentincluding a polymerizable functional group in its molecule; andirradiating the transparent electrode substrate with light having aregular intensity distribution to cause phase-separation between theliquid crystal and the photopolymerizable liquid crystal through aphotopolymerization reaction, thereby forming the polymeric wallincluding at least part of the chiral agent and the crystal regions.

Alternatively, this invention provides a liquid crystal displayinput/output device comprising a liquid crystal display device includinga polymeric wall formed in a pattern between a pair of electrodesubstrates and liquid crystal regions at least partly surrounded by thepolymeric wall; and input means for detecting a position of a desiredpoint by touching the desired point.

In one embodiment, a plurality of liquid crystal domains are formed in apixel, and each of the liquid crystal domains includes at least twoareas having different alignment directions from each other.

In one embodiment, the liquid crystal display device is one of a TNmode, an STN mode and an FLC mode.

In one embodiment, the polymeric wall is tightly attached to theelectrode substrates.

In one embodiment, electrodes on the electrode substrates in the liquidcrystal display device work as an input detection electrode in a liquidcrystal display integrated tablet.

In one embodiment, the input means adopts one of an electromagneticinduction system, an electrostatic induction system and a pressuresensitive system.

In producing the present liquid crystal display device, a mixture ofliquid crystal and a photopolymerizable material is injected between apair of electrode substrates, and the mixture is irradiated with lightso that a portion of the mixture where a liquid crystal region is to beformed be weakly irradiated.

As a result, a reaction is caused first in the components in thephotopolymerizable material (i.e., photopolymerizable liquid crystal anda polymerizable compound(s)) that is strongly irradiated to form a corefor a polymeric wall. Then, since the concentration of the polymerizablecompound is decreased in this strongly irradiated area to cause aconcentration gradient, an unreacted part of the polymerizable compoundpresent in the weakly irradiated area is collected in the stronglyirradiated area in accordance with the concentration gradient and ispolymerized there. Thus, the polymeric wall is formed so as to be incontact with the pair of electrode substrates. Liquid crystal regionsare formed in an area where no polymeric wall is formed.

Since the polymeric wall is tightly attached to the electrode substratesin this manner, the cell thickness is little varied even when anexternal pressure is applied to the electrode substrates.

Moreover, by adopting the above-mentioned configuration, a non-pixelportion, which is an isotropic phase in a conventional device, isaligned in the same manner as in the liquid crystal regions, namely,components in the polymeric wall are allowed to have a birefringentcharacteristic in the same alignment state as that of the liquid crystalregions. Accordingly, the light transmission is approximately the samein the liquid crystal regions and in the polymeric wall. As a result,the non-pixel portion is bright under application of no voltage, andparticularly in a reflective type liquid crystal display device, thedisplay is generally bright. Moreover, since the polymeric wall forsurrounding the liquid crystal regions is formed by causingphase-separation between the liquid crystal and the polymerizablematerial between the electrode substrates, the attachment of thepolymeric wall to the electrode substrates is stronger than in theconventional liquid crystal display device produced by previouslyforming a polymeric wall (partition) on one of the substrates.Accordingly, it is possible to provide a supporting force against anexternal pressure applied by the pen entry or the like, resulting inpreventing display irregularity caused by the variation in the cellthickness due to an external pressure. Therefore, the present liquidcrystal display device is applicable to a pen entry type display devicehaving a pen detective keyboard.

Moreover, when a chiral agent is provided to the polymeric wall and theliquid crystal regions so that one of the following relationships issatisfied, the brightness under application of no voltage is effectivelyimproved: P_(P) <10×P_(LC), wherein P_(P) is a chiral pitch of thepolymeric wall and P_(LC) is a chiral pitch of the liquid crystalregion; and Δn_(P) >(1/10)×Δn_(LC), wherein Δn_(P) is index refractionanisotropy of the polymeric wall and Δn_(LC) is index refractionanisotropy of the liquid crystal region.

Further, when an optical portion such as a photomask is provided withinthe liquid crystal display device, the distance between the displaymedium and the optical portion becomes smaller by the thickness of thesubstrate than in a device having a photomask on the outer surface ofthe substrate. As a result, the polymeric wall is prevented from beingformed in a pixel due to light diffraction. This results not only ingreater brightness in the pixel but also in simplification of theproduction procedure because the photomask is not required to beprovided. Moreover, when the light transmission of the optical portionis controlled by varying the thickness thereof or the like, the liquidcrystal is more excellently phase separated from the polymerizablematerial, resulting in forming well separated liquid crystal regions andpolymeric walls.

Thus, the invention described herein makes possible the advantages ofproviding a liquid crystal display device in which the cell thickness islittle varied by an external pressure, and a production method for thesame.

These and other advantages of the present invention will become apparentto those skilled in the art upon reading and understanding the followingdetailed description with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a liquid crystal display device accordingto Example 1 of the invention.

FIG. 2 is a plane view of a photomask used in Example 1.

FIG. 3 illustrates liquid crystal regions and a polymeric wall formed inExample 1.

FIG. 4 is a sectional view of a reflective type liquid crystal displaydevice to which the present invention is applied.

FIG. 5 is a sectional view of a liquid crystal display device accordingto Example 2, i.e., a self-alignment type liquid crystal display deviceincluding a photomask in its cell.

FIG. 6 is a graph of the absorption curve of a photopolymerizationinitiator used in Example 2.

FIG. 7 is a graph of the absorption curve of a plastic substrate used inExample 2.

FIG. 8 illustrates optical axes of a polarizing plate and a phase plateand the alignment direction of liquid crystal in a reflective typeliquid crystal display device.

FIG. 9 is a sectional view of a typical cell structure in Example 5.

FIG. 10 is a sectional view of the plastic STN liquid crystal displaydevice of Specific Example 1.

FIG. 11 is a plane view of a photomask used in Specific Example 1.

FIG. 12 is a sketch of a polarizing microphotograph of a liquid crystaldisplay device of Specific Example 1.

FIGS. 13A, 13B and 13C show a circuit configuration of a liquid crystaldisplay input/output device used in some examples of the invention, aschematic diagram of a conventional liquid crystal display input/outputdevice, and a schematic diagram of a liquid crystal display input/outputdevice of the electrostatic induction system used in an example of theinvention, respectively.

FIG. 14 is a sectional view of a reflective type STN liquid crystaldisplay device of Specific Example 2.

FIG. 15 is a plane view of a reflecting plate used in Specific Example2.

FIG. 16 is a graph of the absorption curve of a photopolymerizationinitiator used in Specific Example 2.

FIG. 17 is a sectional view of a liquid crystal display device ofSpecific Example 3.

FIG. 18 is a plane view of a photomask used in Specific Example 3.

FIG. 19 is a sketch of a polarizing microphotograph of a liquid crystalregion formed in a liquid crystal display device of Specific Example 3.

FIG. 20 is a sectional view of a reflective type STN liquid crystaldisplay device of Example 6.

FIG. 21 is a sketch of a polarizing microphotograph of a liquid crystaldisplay device of Specific Example 5.

FIG. 22 is a plane view of a photomask used in Specific Example 5.

FIG. 23 is a diagram showing the configuration of reflecting plates in asubstrate used in Specific Example 8.

FIG. 24 shows optical axes of polarizing plates and a phase plate andthe alignment direction of liquid crystal in a transmissive type liquidcrystal display device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described by way of examples.

Example 1

FIG. 1 is a sectional view of an STN liquid crystal display deviceaccording to Example 1 of the invention. This liquid crystal displaydevice is a transmissive type, and includes a cell 1 including a displaymedium 10 sandwiched between substrates 2 and 6 both bearing electrodes.On the outer surfaces of the substrates 2 and 6 constituting the cell 1are respectively provided polarizing plates 14 and 14'. On the innersurface of the substrate 2, which is constituted from a base substrate 3made from an insulated substrate such as glass or the like, are formedstriped lower electrodes 4 and an alignment film 5 in this order fromthe base substrate 3. On the inner surface of the substrate 6, which isconstituted from a base substrate 7 also made from an insulatedsubstrate such as glass or the like, are formed striped upper electrodes8 and an alignment film 9 in this order from the base substrate 7.

The display medium 10 sandwiched between the substrates 2 and 6 includesliquid crystal regions 11 each in the shape of a droplet surrounded by apolymeric wall 12. The alignment state of the liquid crystal region 11is the STN alignment. The polymeric wall 12 is tightly attached oradhered to the substrates 2 and 6.

The method for producing the above-mentioned liquid crystal displaydevice will now be described. First, a photopolymerizable liquid crystalA, i.e., a photopolymerizable compound having liquid crystallinity,(Δε<0) having a polymerizable functional group in its molecule as isrepresented by the following Formula 1 was synthesized as follows:##STR1## First, 4'-hydroxy-2,3-difluorobiphenyl was esterified withexcessive 1,10-dibromodecane in the presence of calcium carbonate. Theresultant was purified through column chromatography, and the obtainedpurified material was mixed with equimolar tetramethyleneammonium-hydroxy pentahydrate. The obtained mixture was esterified withacrylic acid. Thus, the photopolymerizable liquid crystal A wasobtained.

After the synthesis of the photopolymerizable liquid crystal A, thesubstrates 2 and 6 were manufactured as follows: On the surfaces of thesubstrates 3 and 7 each having a thickness of, for example, 1.1 mm werecoated with ITO (a mixture of indium oxide and tin oxide) so as torespectively form the striped lower electrodes 4 and the striped upperelectrodes 8 each with a thickness of 500 angstrom (Å). The resultantsubstrates 3 and 7 were subjected to spin coating with polyimide(Sunever 150; manufactured by Nissan-Chemical Industries Ltd.) torespectively form the alignment films 5 and 9, which were then subjectedto a rubbing treatment with a nylon cloth. The substrates 2 and 6 werethus produced. The number of the lower and the upper electrodes 4 and 8formed per 1 mm was eight, and the interval therebetween was 25 μm.

After the rubbing treatment, the substrates 2 and 6 were attached toeach other so that the directions of the rubbing treatment on therespective substrates crossed at 240°. At this point, a spacer with adiameter of 9 μm was interposed therebetween so as to attain a constantcell thickness. Thus, the cell 1 was produced.

On the thus produced cell 1, a photomask 120 having light shieldingportions 120a and a transparent portion 120b as shown in FIG. 2 wasplaced so that each of the shielding portions 120a cover each pixel inthe cell 1. After or before the placement of the photomask 120, thefollowing mixture was injected into the cell 1 by capillary injection:0.10 g of R-684 (manufactured by Nippon Kayaku Co., Ltd.), 0.05 g ofstyrene, 0.10 g of isobornyl acrylate as polymerizable compounds; 0.75 gof the photopolymerizable. liquid crystal A, 4 g of a liquid crystalmaterial ZLI-4427 (wherein the twist angle was previously adjusted to be240° by adding a chiral agent S-811 (manufactured by Merck & Co.,Ltd.)), and 0.025 g of a photopolymerization initiator Irgacure 651. Toobtain the mixture, the respective components were homogeneously mixedat an isotropic temperature of 54° C. Among the components of themixture, the polymerizable compounds and the photopolymerizable liquidcrystal A work together as the photopolymerizable material.

Then, the cell 1 containing the mixture was subjected to irradiationwith UV rays through the photomask by using a high pressure mercury lampemitting collimated light at 10 mW/cm² for 90 seconds, while maintainingthe temperature thereof at 60° C. Under these conditions, UV raysirradiate the cell 1 in a spatially regular pattern.

Then, the cell 1 was cooled to a temperature of 25° C., where the liquidcrystal is in the nematic state, and was subjected to UV-ray irradiationfor another three minutes continuously, thereby polymerizing thephotopolymerizable material. The cell 1 was then heated to a temperatureof 100° C., and annealed to a temperature of 25° C. over 8 hours. Duringthis procedure, the liquid crystal molecules are aligned in accordancewith the alignment regulating force on the substrate, resulting in animproved display quality.

The polarizing plates 14 and 14' were attached to the thus produced cell1 as shown in FIG. 1. At this point, the polarizing plates 14 and 14'were positioned so that the polarization directions cross the rubbingdirection at 45° and cross each other at 105°. In this manner, atransmissive type STN liquid crystal display device of a yellow modeusing no phase plate was produced.

FIG. 3 shows the display medium 10 in the cell 1 observed with apolarizing microscope. As shown in FIG. 3, the liquid crystal regions 11are formed in accordance with the pattern on the photomask and in asimilar structure to that of a conventional STN liquid crystal displaydevice produced in Comparative Example 1 described below. Further, thephotopolymerizable material (resin), i.e., the photopolymerizable liquidcrystal and the polymerizable compounds, are reacted with thephotopolymerization initiator to be polymerized, and hence, thepolymeric wall 12 includes a liquid crystalline polymer produced throughthe polymerization of the photopolymerizable liquid crystal A.

Table 1 shows the electro-optical characteristic of the liquid crystaldisplay device manufactured in Example 1 together with those of devicesmanufactured in Comparative Examples 1 and 2 described below.

                  TABLE 1                                                         ______________________________________                                                         Comparative                                                                             Comparative                                        Example 1        Example 1 Example 2                                          ______________________________________                                        Contrast                                                                              7            12        3                                              ______________________________________                                    

Comparative Example 1

An STN liquid crystal display device of Comparative Example 1 wasmanufactured by using the same type of a cell manufactured in Example 1and injecting the same type of liquid crystal material (i.e., themixture of the liquid crystal material and the chiral agent used inExample 1) alone into the cell. Polarizing plates were attached to theresultant cell in the same manner as in Example 1. The electroopticalcharacteristic of the liquid crystal display device is shown in Table 1.

Comparative Example 2

A liquid crystal display device of Comparative Example 2 wasmanufactured by using the same type Of a cell manufactured in Example 1and injecting the same type of a mixture used in Example 1 into thecell. The resultant cell was subjected to UV-ray irradiation in the samemanner as in Example 1 except that no photomask was used. Theelectro-optical characteristic of the liquid crystal display device isshown in Table 1.

As is understood from Table 1, the electro-optical characteristic of theliquid crystal display device of Example 1 is as good as that of theconventionally used liquid crystal display device of ComparativeExample 1. The electro-optical characteristic of the liquid crystaldisplay device of Example 1 shown in Table 1 was measured on the liquidcrystal display device including the polymeric wall 12, which decreasesthe contrast. When the polymeric wall 12 was covered with a black mask,the contrast was as high as that of the liquid crystal display device ofComparative Example 1. Further, a pressure with a pen against the liquidcrystal display device little varied the color of the display.

In order to check the tight attachment between the polymeric wall 12 andthe substrates 2 and 6, a portion in the shape of a square of 20 mm×20mm including the polymeric wall 12 and the liquid crystal regions 11alone was cut out from the liquid crystal display device. The substrateattached to the polymeric wall 12 was pulled, but could not be peeledoff with ease. The same procedure was performed with regard to theliquid crystal display device of Comparative Example 1, in which thesubstrate was peeled off with ease because of the lack of the polymericwall.

The liquid crystal display device of Comparative Example 2 has a lowercontrast. It is assumed, through the observation with a polarizingmicroscope, that the contrast is decreased because the polymeric wallwas partially formed within a pixel.

Since the polymeric wall 12 in the liquid crystal display device ofExample 1 is tightly attached or adhered to the substrates 2 and 6, itis different from the polymeric wall previously formed before theattachment of the substrates disclosed in Japanese Laid-Open PatentPublication No. 4-323616. Further, since the polymeric wall 12 istightly attached or adhered to the substrates 2 and 6, the variation inthe cell thickness caused by an external pressure is suppressed.Therefore, it is possible to avoid the change in the display color andthe like otherwise causes in the pen entry. In addition, the resistanceagainst shock when dropped or the like is extremely improved. Further,when the liquid crystalline polymer having the same effect as thealignment regulating force on the substrate is contained within thepolymeric wall 12, the alignment state of the liquid crystal isextremely stabilized because the alignment regulating force works bothin the horizontal direction from the substrate and in the verticaldirection from the polymeric wall 12. Furthermore, since almost all theportion of the polymeric wall 12 is intentionally formed in a non-pixelportion, the contrast decrease due to the polymeric material can besuppressed as compared with the case where a polymeric wall is formed atrandom. Further, a polymeric thin film is sometimes formed on theinterface between the liquid crystal region 11 and the substrate 2 or 6.In this case, the liquid crystal molecules are uniformly orientedbecause the alignment regulating force on the substrate is transferredto the liquid crystal molecules through the polymeric thin film. Inaddition, since the liquid crystal region 11 is three-dimensionallysurrounded by the polymeric material in this case, the liquid crystaldisplay device achieves a higher resistance against external pressure.

Since the polymeric wall 12 can be formed approximately isotropically,the polymeric wall in the non-pixel portion can work as a black maskwhen two polarizing plates whose polarization axes cross at right anglesare used. When a phase plate having a pattern for each pixel is providedto the liquid crystal display device, a high contrast can be attained.

The liquid crystal display device of Example 1 is suitable to atransmissive type liquid crystal display device. The present invention,however, is not limited to the transmissive type and can be applied to areflective type STN liquid crystal display device. FIG. 4 is a sectionalview of a reflective type liquid crystal display device to which thepresent invention is applied. This liquid crystal display deviceincludes one polarizing plate as disclosed in Japanese Laid-Open PatentPublication Nos. 4-289818 and 4-97121. In the liquid crystal displaydevice of FIG. 4, a phase plate 13 is provided between a cell 1 and apolarizing plate 14. A substrate 2 includes a base substrate 3 havingprojections 17 on the inner surface facing a display medium 10. Aleveling film 16 is formed on approximately the entire surface of thesubstrate 3 so as to cover the projections 17. On the leveling film 16are formed striped lower electrodes 15 made from a reflective metalfilm.

Example 2

FIG. 5 is a sectional view of a liquid crystal display device accordingto Example 2. This liquid crystal display device includes, in additionto the components of the device of Example 1 shown in FIG. 1, areflecting plate 20 on the substrate 2 having a reflecting portion on aposition corresponding to each pixel, a color filter 18 and a protectionfilm 19 both on the substrate 6. The substrates 2 and 6 of Example 2 aremade from an acrylic plastic substrate bearing an ITO film with a totalthickness of 400 μm.

The liquid crystal display device was manufactured as follows: First,the substrates 2 and 6 as above were manufactured, and the alignmenttreatment was conducted in the same manner as in Example 1.

The substrates 2 and 6 were attached to each other in the same manner asin Example 1 using a spacer with a diameter of 5.8 μm, and the followingmixture was injected into the thus produced cell: 0.10 g of R-684(manufactured by Nippon Kayaku Co., Ltd.), 0.01 g of styrene, 0.14 g ofisobornyl acrylate as polymerizable compounds; 0.75 g of thephotopolymerizable crystal liquid A, 4 g of the liquid crystal materialZLI-4427 (wherein the twist angle was previously adjusted to be 240° byadding the chiral agent S-811 (manufactured by Merck & Co., Ltd.)), and0.025 g of a photopolymerization initiator Lucirin TPO (manufactured byBASF; exhibiting largest light absorption around 400 nm as shown withcrosshatch in FIG. 6). The mixture was injected into the cell by vacuuminjection, for example, at a pressure of 100 Pa. at a temperature of 30°C. and by raising the temperature of the substrates and the usedinjection plate up to 60° C. simultaneously with the start of theinjection. The polymerizable compounds and the photopolymerizable liquidcrystal A work together as the photopolymerizable material.

Then, the cell was heated to a temperature of 80° C., and subjected toUV-ray irradiation through the reflecting plate 20 for 3 minutes at thesame UV-ray intensity as in Example 1. The cell was then cooled to atemperature of 25° C., and subjected to the UV-ray irradiation again foranother 7 minutes. The cell was then heated to a temperature of 100°C.,and annealed to 25° C. over 8 hours. The retardation of the thusproduced duced cell 1 (Δn₁ ·d₁) was 650 nm. The substrates 3 and 7formed from an acrylic plastic substrate bearing the ITO film have anabsorption curve as shown in FIG. 7, and substantially cut light below350 nm.

Next, the polarizing plate 14 and the phase plate 13 (Δn₂ ·d₂ =350 nm)e.g., a retardation film were attached to the cell 1 in the relationshipas shown in FIG. 8. Thus, a reflective type STN liquid crystal displaydevice including one polarizing plate was produced. FIG. 8 will bedescribed in detail below.

The thus produced liquid crystal display device exhibits the same effectas that of the liquid crystal display device of Example 1. In addition,since the transparent portion of the used reflecting plate 20corresponds with the photomask used in Example 1, the liquid crystaldisplay device has a configuration as if it included a photomask thereinalthough a photomask is not actually used. In this display device, thedistance between the liquid crystal region and the portion working as aphotomask is smaller by the thickness of the substrate than inExample 1. Therefore, a polymeric wall is prevented from being formed ina pixel due to the diffraction caused by the photomask, resulting in asimplified production procedure.

Table 2 shows the electro-optical characteristics of the liquid crystaldisplay device of Example 2 together with those of Examples 3 and 4, andComparative Examples 3 and 4. The characteristics were measured by usinga ratio of a reflectance of light entering at an angle of 30° againstthe normal line of the liquid crystal display device to a reflectance ofwhite light in the direction of the normal line.

                  TABLE 2                                                         ______________________________________                                                                       Com.   Com.                                    Example      Example  Example  Example                                                                              Example                                 2            3        4        3      4                                       ______________________________________                                        Contrast                                                                              6        3.5      4.5    1.6    2.8                                   d · Δn(nm)                                                             650      515      784    448    896                                   ______________________________________                                    

Examples 3 and 4 and Comparative Examples 3 and 4

Reflection type liquid crystal display devices of Examples 3 and 4 andComparative Examples 3 and 4 were produced by using the same type ofsubstrates in the same manner as in Example 2 except that the diameterof the spacers was 4.6 μm in Example 3, 7.0 μm in Example 4, 4.0 μm inComparative Example 3, and 8.0 μm in Comparative Example 4 instead of 9μm in Example 2. By varying the diameter of the spacers in this manner,the retardation of the resultant liquid crystal display devices wasvaried. The twist angle of the used liquid crystal was previouslyadjusted to be 240° by adding S-811.

As is understood from Table 2, the liquid crystal display devices of theExamples 2, 3 and 4 have an improved contrast as compared with those ofComparative Examples 3 and 4.

The present liquid crystal display device represented by the liquidcrystal display devices of Examples 1 through 4 have sharpness in theelectro-optical characteristics. Therefore, it is possible to attain asufficient duty ratio, eliminating the need for a TFT. Thus, theproduction cost can be decreased. Further, since the polymeric wall isformed in the cell, the cell thickness is little varied by externalpressure applied by pen entry or the like, thereby causing littledisplay irregularity.

Example 5

FIG. 9 is a sectional view of a liquid crystal display input/outputdevice according to Example 5. The liquid crystal display input/outputdevice includes two glass substrates 23 each having a thickness of 1.1mm. One of the substrates (the upper substrate) has the followingconfiguration: On one of the glass substrates 23 are formed a pluralityof transparent electrodes 24 from ITO in a matrix. An alignment film 25is formed so as to cover the transparent electrodes 24. The othersurface of this glass substrate 23 is provided with a polarizing plate22 and an input device 21.

The other of the substrates (the lower substrate) has the followingconfiguration: On the other glass substrates 23 are also formed aplurality of the transparent electrodes 24 made from ITO. The alignmentfilm 25 is also provided over the transparent electrodes 24. The othersurface of this glass substrate 23 is provided with another polarizingplate 22.

The above described two glass substrates 23 sandwich a display mediumlayer. In the display medium layer, a polymeric wall 26 is formed on aportion excluding the portions of the transparent electrodes 24, and aliquid crystal portion 27 is formed on a portion surrounded by thepolymeric wall 26 and corresponding to each transparent electrode 24through a production procedure described below. The substrates 23 areattached to each other with the display medium layer sandwichedtherebetween using a spacer (not shown) in the shape of, for example, asphere or a cylinder interposed therebetween, thereby attaining aconstant cell thickness.

In the aforementioned liquid crystal display input/output device ofExample 5, the liquid crystal region 27 substantially surrounded by thepolymeric wall 26 between the glass substrates 23 bearing thetransparent electrodes 24 has a micro cell structure, as shown in FIG.9. Further, since the polymeric wall 26 is adhered to the glasssubstrates 23, the resistance of the device against external pressure ismuch higher. This high shock resistance is exhibited, for example, whenthe device is dropped. Moreover, the variation in the cell thickness dueto an external pressure is suppressed by the polymeric wall 26, and thedisplay color is prevented from changing even when the device is pressedin the pen entry or the like. Further, when the polymeric liquid crystalhaving the same effect as the alignment regulating force on thesubstrate is contained in the polymeric wall 26, the alignment state ofthe liquid crystal is extremely stabilized because the alignmentregulating force works both in the horizontal direction from thealignment film 25 on the substrate 23 and in the vertical direction fromthe polymeric wall 26. Furthermore, since almost all the portion of thepolymeric wall 26 is intentionally formed in a non-pixel portion, thecontrast decreases due to the polymeric material can be suppressed ascompared with the case where a polymeric wall is formed at random.

Now, Specific Examples and Comparative Examples of Example 5 will bedescribed, although the present invention is not limited to theseSpecific Examples.

Specific Example 1

1) Synthesis of a polymerizable liquid crystal having a polymerizablefunctional group in its molecule:

A compound B (having Δε<0) represented by the following Formula 2 issynthesized as follows: ##STR2## First 4'-hydroxy-2,3-difluorobiphenylwas esterified with excessive 1,12-dibromododecane in the presence ofcalcium carbonate. The resultant was purified through columnchromatography, and the obtained purified material was mixed withequimolar tetramethylene anmonium-hydroxy pentahydrate. The obtainedmixture was esterified with acrylic acid.

2) Production of a cell:

The structure of a liquid crystal display input/output device ofSpecific Example 1 will be described referring to a sectional view ofFIG. 10. As an upper substrate, on the surface of a glass substrate 23having a thickness of 1.1 mm were formed striped transparent electrodes24 from ITO so as to have a thickness of 500 Å (eight electrodes/mm; aninterval of 25 μm). Then, the resultant substrate 23 was coated by spincoating with polyimide (Sunever 150; manufactured by Nissan ChemicalIndustries Co., Ltd.), which was then subjected to the rubbing treatmentwith a nylon cloth in one direction, thereby forming an alignment film25 on the substrate 23. A lower substrate is formed in the same manneras the upper substrate. The resultant substrates 23 were attached toeach other so that the alignment directions thereon cross at 240° with aspacer (not shown) having a diameter of 9 μm interposed therebetween.Thus, a cell was produced.

The cell was provided with a photomask 37 having a dot pattern. The usedphotomask included, as shown in FIG. 11, a plurality of light shieldingportions 28 each having a size of, for example, 100 μm×100 m arranged ina matrix and a transparent portion 29 having a width of 25 μmsurrounding the light shielding portions 28. The photomask 37 wasprovided on the cell so that each pixel in the cell was shielded, andthe following mixture was injected into the resultant cell: 0.10 g ofR-684 (manufactured by Nippon Kayaku Co., Ltd.), 0.05 g of styrene, 0.75g of the compound B, 0.10 g of isobornyl acrylate, 4 g of a liquidcrystal material ZLI-4427 (wherein the twist angle was previouslyadjusted to be 240° by adding the chiral agent S-811 (manufactured byMerck & Co., Ltd.)), and 0.025 g of a photopolymerization initiatorIrgacure 651.

After mixing these components homogeneously at an isotropic temperatureof 5420 C., the mixture was injected by capillary injection. Then, theresultant cell was subjected to the UV-ray irradiation through the dotpattern on the photomask by using a high pressure mercury lamp emittingcollimated light at 10 mW/cm² for 90 seconds at a temperature of 60° C.Then, the cell was cooled to a temperature of 25° C., and subjected tothe UV-ray irradiation again for another 3 minutes continuously, therebypolymerizing the polymerizable material. Then, the cell was heated to atemperature of 100° C., and annealed to a temperature of 25° C. over 8hours.

The observation of the thus produced liquid crystal cell with apolarizing microscope found liquid crystal regions 30 in the samepattern as that of the photomask and a polymeric region 31 as shown inFIG. 12 The liquid crystal region 30 had the similar structure as thatof a conventional STN liquid crystal display device produced inComparative Example 5 described below. To the thus produced cell wereattached a phase plate and polarizing plates 22 so that the polarizationdirections cross the rubbing direction at 45° and each other at 105°,thereby producing a transmissive type STN liquid crystal display device.

When the liquid crystal display device was pressed with a pen or thelike, the display color was little varied.

The thus produced liquid crystal display device was connected with acircuit for a display integrated tablet of an electrostatic inductiontype as shown in FIG. 13A, thereby manufacturing a liquid crystaldisplay input/output device (excluding a protection panel). The displayquality was little varied by a pen entry operation. The liquid crystaldisplay input/output device shown in FIGS. 13A through 13C will bedescribed in detail below.

Comparative Example 5

Into the same type of a cell produced in Specific Example 1, the liquidcrystal material (the mixture of the liquid crystal and the chiral agentused in Specific Example 1) alone was injected, thereby manufacturing aliquid crystal display device of Comparative Example 5. Polarizingplates were attached to the liquid crystal display device in the samemanner as in Specific Example 5, thereby manufacturing a conventionalSTN liquid crystal display device. The STN liquid crystal display devicewas connected with a circuit for the display integrated tablet of theelectrostatic induction system as shown in FIG. 13A, thereby producing aliquid crystal display input/output device. Through the pen entryoperation, display irregularity such as reverse contrast viewing wascaused by the pressure with the pen. The display irregularity wasespecially conspicuous in displaying black.

Specific Example 2

A liquid crystal display input/output device. according to SpecificExample 2 will be described referring to a sectional view of FIG. 14. Onone of two acrylic plastic substrates 23 each having a thickness of 400μm (whose absorption curve is shown in FIG. 7) was provided with areflecting plate 32 having a transparent portion 39 corresponding to theposition of each pixel as shown in FIG. 15. The other substrate 23 had acolor filter 33 and a protection film 34. The same alignment treatmentas in Specific Example 1 was conducted, and the resultant substrates 23were attached to each other with a spacer having a diameter of 5.8 uminterposed therebetween, thereby manufacturing a reflective type cell asshown in FIG. 14.

The mixture to be injected into the cell was the same as that used inSpecific Example 1 except that the photopolymerization initiator alonewas replaced with KAYACURE DETX-S (manufactured by Nippon KayakuIndustries Co., Ltd.) This photopolymerization initiatar has anabsorption curve as is shown in FIG. 16, and causes polymerization withvisible light at 350 through 400 nm. The mixture was injected into thecell by vacuum injection at a pressure of 100 Pa. at a temperature of30° C. and by raising the temperature of the substrates and the usedinjection plate up to 60° C. simultaneously with the start of theinjection. The resultant cell was subjected to UV-ray irradiationthrough the reflecting plate 32 at the same UV-ray intensity as inSpecific Example 1 at a temperature of 80 C. for 10 minutes. Then, thecell was annealed to a temperature of 25° C. over 5 hours. Theretardation (Δn₁ ·d₁) of the thus produced liquid crystal display was650 nm. A polarizing plate 22 and a phase plate 32 a retardation film(Δn₂ ·d₂ =350 nm) were attached to the cell, thereby manufacturing areflective type STN liquid crystal display device including onepolarizing plate as shown in FIG. 14.

The thus manufactured liquid crystal display device was connected withthe circuit for the display integrated tablet of the electrostaticinduction system as shown in FIG. 13A, thereby producing a liquidcrystal display input/output device (excluding a protection panel), asshown in FIG. 14. The display quality was little changed by the penentry operation.

Comparative Example 6

Into the same type of a cell as that manufactured in Specific Example 2,the same type of liquid crystal material alone (the mixture of theliquid crystal and the chiral agent used in Specific Example 1) wasinjected, thereby manufacturing a cell. A polarizing plate was attachedto the thus manufactured cell in the same manner as in Specific Example2, thereby manufacturing a conventional STN liquid crystal displaydevice (using a plastic substrate). The STN liquid crystal displaydevice was connected with the circuit for the display integrated tabletof the electrostatic induction system as shown in FIG. 13A, therebyproducing a liquid crystal display input/output device.

Through the pen entry operation, display irregularity such as reversecontrast viewing was caused by the pressure with the pen. Further, afterfinishing the display, the alignment of the liquid crystal wasdisordered for several seconds at a portion to which a pressure wasapplied with the pen. The display irregularity was especiallyconspicuous in displaying black.

Specific Example 3

A liquid crystal display input/output device of Specific Example 3 willbe described referring to a sectional view of FIG. 17. A glass substrate23 having a thickness of 1.1 mm and bearing a TFT device 45 andtransparent electrodes 43 of ITO with a thickness of 500 Å was used as alower substrate. Another glass substrate 23 having a thickness of 1.1 mmand bearing transparent electrodes 44 was used as an upper substrate.These two substrates 23 were attached to each other with a spacer (notshown) with a diameter of 6 μm interposed therebetween, therebymanufacturing a cell. The upper substrate can be provided with a colorfilter. The cell was provided with a photomask with a dot pattern havinglight shielding portions 36 and a transparent portion 35 as shown inFIG. 18.

The mixture to be injected into the cell was obtained by mixing 0.1 g ofR-684 (manufactured by Nippon Kayaku Industries Co., Ltd.), 0.05 g ofstyrene, 0.85 g of isobornyl methacrylate, 4 g of the liquid crystalmaterial ZLI-4792 (manufactured by Merck & Co., Ltd.) including 0.4 wt%of S-811, and 0.0025 g of the photopolymerization initiator Irgacure651. The mixture was injected into the cell in a transparent state(i.e., at a temperature of 35° C.). While keeping this temperature, thecell was subjected to UV-ray irradiation through the dot pattern on thephotomask by using a high pressure mercury lamp emitting collimatedlight at 10 mW/cm² for 1 second, and the irradiation was stopped for 30seconds. This cycle of 1 second of irradiation and 30 seconds ofnon-irradiation was repeated 20 times. Then, the cell was subjected tothe UV-ray irradiation again for another ten minutes, therebypolymerizing the polymerizable material.

The observation of the thus manufactured liquid crystal display devicewith a polarizing microscope found that a liquid crystal domain wasformed in the same regularity as the dot pattern on the photomask, i.e.,as the pattern of the electrodes 43.

The thus obtained cell was sandwiched between a pair of polarizingplates 22 so that the polarization axes thereof cross at right angles.In the resultant liquid crystal display device, a liquid crystal region41 was surrounded by a polymeric wall 40. The observation of this liquidcrystal display device with a polarizing microscope found, as shown inFIG. 19, that each pixel included approximately one liquid crystaldomain. In addition, a schlieren texture 42, which is generally observedwhen the liquid crystal molecules are aligned radially orconcentrically, was observed.

Comparative Example 7

Into the same type of a cell as that manufactured in Specific Example 3,the liquid crystal material ZLI-4792 (manufactured by Merck & Co., Ltd.)including 0.4 wt% of S-811 was injected. The cell was provided withpolarizing plates so that the polarization axes be matched with eachother, thereby manufacturing a conventional TN liquid crystal displaydevice.

The tablet of an electrostatic induction system as shown in FIG. 13B wasconnected below the manufactured liquid crystal display device, therebyproducing a liquid crystal display input/output device (excluding aprotection panel on the top surface). Through the pen entry operation,display irregularity such as reverse contrast viewing was caused by thepressure with the pen. The display quality on the portion pressed withthe pen was degraded.

Specific Example 4

A liquid crystal display output/input device according-to SpecificExample 4 will be described referring to the sectional view of FIG. 9.

On the surfaces of two glass substrates 23, transparent electrodes wereformed by evaporating an ITO film with a thickness of approximately 100nm, and the resultant substrates 23 were subjected to a wet etchingprocess, thereby forming a plurality of parallel electrode lines 24 in apattern. The surface of each glass substrate 23 bearing the transparentelectrode lines 24 was subjected to spin coating with polyimide, therebyforming a polyimide alignment film with a thickness of approximately 50nm. The substrate 23 was then sintered for 1 hour at a temperature of190° C., and subjected to a rubbing treatment in one direction, therebyforming an alignment film 25. the rubbing directions were the same onthe both substrates 23 when they were opposed to each other so that thesurfaces bearing the transparent electrode lines 24 face each other andattached to each other so that the electrode lines 24 thereon cross eachother at right angles. The two substrates 23 were attached to each otherin the above-mentioned manner with silica beads (not shown) having adiameter of 2 μm interposed therebetween as a spacer. Thus, the cell ofSpecific Example 4 was produced.

Next, 0.80 g of a ferroelectric liquid crystal material ZLI-4003(manufactured by Merck & Co., Ltd.), 0.02 goof polyethylene glycoldiacrylate (brand name: NK ester A-200; manufactured by Shin NakamuraChemical Industrial Co.,Ltd.) as a polymerizable material (polymerprecursor), and 0.18 g of lauryl acrylate (brand name: NK ester LA;manufactured by Shin Nakamura Chemical Industrial Co.,Ltd.) werehomogeneously mixed, and the mixture was injected into the cell. Thisliquid crystal-polymer precursor mixture is in a nematic phase orisotropic liquid phase at atmospheric pressure. The Curie temperature ofthe mixture is as follows:

    SmC<25° C.<SmA<31° C.<Ch<35° C.<Iso

Next, the cell was provided with a photomask as shown in FIG. 11. Undera condition where the liquid crystal-polymer precursor mixture was inthe nematic phase or the isotropic liquid phase, the cell was subjectedto the UV-ray irradiation through the photomask by using a high pressuremercury lamp emitting collimated light at 10 mW/cm² for 2 minutes. TheUV-ray irradiation photopolymerized the mixture, thereby causingphase-separation between the liquid crystal and the polymeric material.Thus, liquid crystal regions 27 and a polymeric wall 26 were formed.

The observation of the phase-separation with a polarizing microscopefound that the polymeric wall was not formed in a portion shielded bythe photomask but formed in and in the vicinity of a portion irradiatedwith UV rays.

When the cell was observed with a polarizing microscope having a crossednicol, in the center of a liquid crystal droplet formed in the UV-rayshielded portion, a general SSF (surface stabilized ferroelectric) typealignment was found in the rubbing direction on the substrate, and thealignment was sharply changed in the vicinity of the polymeric wall tobe vertical.

The tablet of the electrostatic induction system as shown in FIG. 13Bwas connected below the manufactured liquid crystal display device,thereby producing a liquid crystal display input/output device(excluding a protection panel on the top surface).

Throughout the pen entry operation, display irregularity such as reversecontrast viewing was not caused by the pressure with the pen.

Comparative Example 8

Into the same type of a cell manufactured in Specific Example 4, theferroelectric liquid crystal material ZLI-4003 (manufactured by Merck &Co., Ltd.) was injected. The cell was heated to 120° C., and thenannealed to room temperature, thereby manufacturing a cell. Polarizingplates were attached to the cell so that the polarization axes thereofwere matched with the alignment direction, thereby manufacturing aconventional FLC (ferroelectric liquid crystal) display device. The thusobtained liquid crystal display device was connected with the circuitfor the display integrated tablet of the electrostatic induction systemof FIG. 13A, thereby producing a liquid crystal display input/outputdevice. Throughout the pen entry operation, display irregularity such asreverse contrast viewing was caused by the pressure with the pen.Further, after finishing the display, the alignment of the liquidcrystal was disordered for several seconds at a portion to whichpressured was applied with the pen. The display irregularity wasespecially conspicuous in displaying black.

Example 6

FIG. 20 is a sectional view of a reflective type STN liquid crystaldisplay device according to Example 6. As shown in FIG. 20, a basesubstrate 51 is provided with lower electrodes 52 and an alignment film53. A base substrate 54 is provided with upper electrodes 55 and analignment film 56. A pair of electrode substrates 57 and 58 are thusconstituted. A cell 61 includes a great number of liquid crystal regions60 (areas utilizing the alignment regulating force on the surface of thesubstrates) substantially surrounded by a polymeric wall 59 andsandwiched between the electrode substrates 57 and 58. On the-othersurface of the base substrate 54 than the surface facing the liquidcrystal regions 60 is provided a polarizing plate 62.

In order to form the polymeric wall 59, the transparent electrodesubstrates 57 and 58 are irradiated with UV rays. Due to the transparentelectrodes 52 and 55, which work as optical portions having UV-rayabsorbing property, the irradiating UV rays attain a light intensitydistribution, which causes phase-separation between the liquid crystaland the polymeric material. As a result, the polymeric wall 59 and theliquid crystal regions 60 are formed in accordance with the lightintensity distribution. Since the polymeric wall 59 is tightly attachedand/or adhered to the electrode substrates 57 and 58, and sandwichedtherebetween in this manner, the cell thickness is much less varied byan external pressure, the display color is prevented from changing whenpressed with a pen, and the shock resistance is extremely improved.

Moreover, the components in the polymeric wall 59 have birefringence andare in the same alignment state as in the liquid crystal regions 60.Because of this, the alignment in the polymeric wall 59 is approximatelythe same as that in the liquid crystal regions 60 under application ofno voltage, resulting in approximately the same light transmission inthe liquid crystal regions 60 and the polymeric wall 59.

Particularly in a reflective type liquid crystal display device, thebrightness under application of no voltage is improved.

It is preferable that the index refraction anisotropy Δn_(P) of thepolymeric wall 59 and the index refraction anisotropy Δn_(LC) of theliquid crystal region 60 satisfy the following relationship:

    Δn.sub.P >(1/10)×Δn.sub.LC               (1)

When the index refraction anisotropy of the polymeric wall is smallerthan (1/10)×Δn_(LC), the brightness under application of no voltagecannot be improved because the light transmission through the polymericwall is decreased. The optimal value of the birefringence of the liquidcrystal region 60 under application of no voltage depends upon the modeof the liquid crystal region 60, and hence, the birefringence of theliquid crystal region preferably has an optimal value determined by themode of the formed liquid crystal region.

Further, the chiral pitch of the polymeric wall 59, which is one of thefactors affecting the light transmission, is significant to improve thebrightness under application of no voltage. It is preferable that thechiral pitch P_(P) of the polymeric wall 59 and the chiral pitch P_(LC)of the liquid crystal region 60 satisfy the following relationship:

    P.sub.P <10×P.sub.LC                                 (2)

When the relationship (2) is not satisfied, the brightness underapplication of no voltage is less improved.

The optimal value of the chiral pitch depends upon the mode of theliquid crystal region 60, and the chiral pitch of the liquid crystalregion preferably has an optimal value determined by the mode of theformed liquid crystal region. In adopting a mode where the twist of theliquid crystal is not used, such as the ECB mode, the chiral pitch inthe liquid crystal region 60 under application of no voltage isinfinity.

Now, Specific Examples and Comparative Examples of Example 6 will bedescribed.

Specific Example 5 (Transparent type STN liquid crystal display device)

On the surfaces of two glass substrates each having a thickness of 1.1mm were formed striped transparent electrodes from ITO so as to have athickness of 2000 Å (eight electrodes/mm; an interval of 25 μm). Then,the resultant substrates were coated by spin coating with polyimide(Sunever 150; manufactured by Nissan Chemical Industries Co., Ltd.),which was then subjected to the rubbing treatment with a nylon cloth inone direction. After the rubbing treatment, the resultant substrateswere attached to each other so that the alignment directions thereoncross at 240° with a spacer having a diameter of 9 μm interposedtherebetween. Thus, a cell was produced.

Next, 0.012 g of a compound C (polymerizable chiral agent) representedby the following Formula 3, 0.10 g of p-phenyl styrene, 0.85 g of acompound D represented by the following Formula 4, 0.038 g of1,4butanediol dimethacrylate, 5 g of the liquid crystal ZLI-4427(manufactured by Merck & Co., Ltd.; wherein the twist angle waspreviously adjusted to be 240° by adding S-811), and 0.025 g of thephotopolymerization initiator Irgacure 651 were homogeneously mixed. Theobtained mixture was injected into the cell by pillary injection. Thethus produced cell was irradiated with UV rays from both sides by usingtwo high pressure mercury lamps emitting collimated light at 10 mW/cm²for 4 minutes at a temperature of 60° C. Under these conditions, sincethe difference in intensity of UV rays occurs between the portion wherethe ITO electrodes exist and the portion where the ITO electrodes do notexist, the irradiating UV rays had a light intensity distribution withspatial regularity. Then, the cell was cooled to a temperature of 20°C., where the liquid crystal was in the nematic state. The cell wassubjected to the UV-ray irradiation again for another 3 minutescontinuously, thereby polymerizing the polymerizable material. The cellwas then heated up to a temperature of 100° C. and annealed to 25° C.over 8 hours. Through this procedure, the liquid crystal molecules werealigned in accordance with the alignment regulating force on thesubstrate, thereby improving the display quality of the resultant liquidcrystal display device. ##STR3## wherein * indicates an asymmetriccarbon atom. ##STR4##

The observation of the thus produced cell with a polarizing microscopefound, as shown in FIG. 21, that liquid crystal regions 71 and apolymeric wall 72 were formed in accordance with the pattern of overlaidportion of the upper and lower ITO electrodes (100 μm ×100 μm) and thatthe liquid crystal regions 71 had the similar structure as that of aconventional STN liquid crystal display device manufactured inComparative Example 9 described below. This means that the ITOelectrodes work as means including light shielding portions 74 each inthe shape of a square of 100 μm ×100 μm surrounded by a transparentportion 75 having a width of 25 μm as shown in FIG. 22.

To the thus produced cell were attached polarizing plates so that thepolarization directions cross the rubbing direction at 45° and crosseach other at 105°, thereby producing a transmissive type STN liquidcrystal display device. Since the photopolymerizable liquid crystal waspolymerized in the polymeric wall, the polymeric wall contained a liquidcrystalline polymer. Accordingly, it was observed that also thepolymeric wall was transmissive.

The transmission ratio under application of no voltage of the thusproduced liquid crystal display device is indicated as a ratio to thatof a liquid crystal display device produced in Comparative Example 9described below whose transmission is taken as 100, and listed in Table3 below.

                  TABLE 3                                                         ______________________________________                                        Transmission ratio under application of no                                    voltage:                                                                      Spec.  Spec.    Spec.     Com.   Com.   Com.                                  Example                                                                              Example  Example   Example                                                                              Example                                                                              Example                               5      6        7         10     11     12                                    ______________________________________                                        89     86       81        24     70     71                                    ______________________________________                                    

As is understood from Table 3, the electrooptical characteristics of theliquid crystal display device of Specific Example 5 are as good as thoseof the conventionally used liquid crystal display device manufactured inComparative Example 9. In addition, when the present liquid crystaldisplay device was pressed with a pen, the display color was littlechanged.

In order to check the tight attachment between the polymeric wall andthe substrates, a portion in the shape of a square of 20 mm ×20 mmincluding the polymeric wall and the liquid crystal regions alone wascut out from the cell. The substrate attached to the polymeric wall waspulled, but could not be peeled off with ease. The same procedure wasperformed with regard to the cell of Comparative Example 9, but thesubstrate was peeled off while cutting the square portion.

By using the same type of mixture of the photopolymerizable material andthe photopolymerization initiator, the chiral pitch of the polymericmaterial obtained from the mixture was estimated by using a wedge typecell. Further, the photopolymerizable material alone was polymerizedbetween vertical alignment films and between horizontal alignment films,thereby estimating Δn by using an Abbe refractometer. The estimated Δnand chiral pitch (μm), which are the characteristics of the polymericmaterial after the polymerization, are listed in Table 4 below.

                  TABLE 4                                                         ______________________________________                                                        Δ n                                                                          Chiral pitch (μm)                                     ______________________________________                                        Comparative Example 11                                                                          ≈0                                                                           0                                                    Comparative Example 12                                                                          ≈0                                                                           0                                                    Specific Example 5                                                                              0.052  22                                                   Specific Example 6                                                                              0.044  22                                                   Specific Example 7                                                                              0.017  22                                                   ZLI-4427          0.112  14                                                   ______________________________________                                    

Comparative Example 9

Into the same type of a cell manufactured in Specific Example 5, thesame type of the liquid crystal material (the mixture of the liquidcrystal and the chiral agent used in Specific Example 5) alone wasinjected, thereby manufacturing a cell. Polarizing plates were attachedto the cell in the same manner as in Specific Example 5, therebymanufacturing a conventional STN liquid crystal display device. Theelectro-optical characteristics of this liquid crystal display device istaken as 100 to be used as a standard for the characteristics listed inTable 3 above.

Comparative Example 10

Into the same type of cell as that manufactured in Specific Example 5,the same type of a mixture as used in Specific Example 5 was injected.The thus manufactured cell was subjected to the UV-ray irradiationwithout using a photomask in the same manner as in Specific Example 5,thereby manufacturing a liquid crystal display device.

The electro-optical characteristics of the liquid crystal display deviceare listed in Table 3 above. The observation of the liquid-crystaldisplay device found that a polymeric wall was formed within a pixel,which is assumed to be the reason for the decreased contrast.

Comparative Examples 11 and 12 and Specific Examples 6 and 7

Liquid crystal display devices of these examples were manufactured byusing the same type of cell, a liquid crystal and a photopolymerizationinitiator as those used in Specific Example 5, and the UVray irradiationwas also conducted in the same manner as in Specific Example 5. Thecomposition ratio of the photopolymerizable material to be injectedtogether with the liquid crystal and the photopolymerization initiatorinto the respective cells was, however, different from that of SpecificExample 5 and is listed in Table 5 below. The electro-opticalcharacteristics of the manufactured liquid crystal display devices arelisted in Table 3 above.

                  TABLE 5                                                         ______________________________________                                        Composition ratio of the photopolymerizable                                   material (wt %):                                                              Compound      Compound  p-phenyl-      Lauryl                                 C             D         styrene  R-684 acrylate                               ______________________________________                                        Com.    0         0         10     5     85                                   Example 11                                                                    Com.    0         10        10     5     75                                   Example 12                                                                    Spec.   1.2       85        10     3.8   0                                    Example 5                                                                     Spec.   1.2       75        10     3.8   10                                   Example 6                                                                     Spec.   1.2       65        10     3.8   20                                   Example 7                                                                     ______________________________________                                    

Further, the Δn and the chiral pitch (μm) of each photopolymericmaterial after the polymerization are also listed in Table 4 above.

Specific Example 8 (Using a plastic substrate in a reflective type STNliquid crystal display device)

Two acrylic plastic substrates each having a thickness of 400 μm weresubjected to the same alignment treatment as in Specific Example 5, andwere attached to each other with a spacer having a diameter of 5.8 μminterposed therebetween in the same manner as in Specific Example 5. Theabsorption curve of the plastic substrate is shown in FIG. 7 and thesubstrate substantially cuts light under 350 nm. One of the plasticsubstrates was provided with a reflecting plate having reflectingportions 81 in a matrix corresponding to pixels and a transparentportion 82 surrounding the reflecting portions 81 as shown in FIG. 23.The other substrate was provided with a color filter. Thus, a reflectivetype cell was manufactured. Since the cell included the transparentportion 82 between the reflecting plates 81, the effect of a photomaskcan be attained without using an actual photomask. In this system, thedistance between the liquid crystal layer and the portion working as aphotomask is smaller by the thickness of the substrate as in SpecificExample 5. Therefore, a polymeric wall is prevented from being formed ina pixel due to the diffraction caused by the photomask, and productionprocedure can be simplified.

Next, a mixture including 0.009 g of the compound C (polymerizablechiral agent), 0.10 g of pphenyl styrene, 0.85 g of the compound D,0.041 g of 1,4-butanediol dimethacrylate, 5 g of the liquid crystalmaterial ZLI-4427 (manufactured by Merck & Co-, Ltd.; wherein the twistangel is previously adjusted to be 240° by adding S-811) and 0.025 g ofa photopolymerization initiator Lucirin TPO (manufactured by BASF;exhibiting its largest absorption around 400 nm) was injected into thecell by vacuum injection at a pressure of 100 Pa. at a temperature of30° C. and by raising the temperature of the substrates and the usedinjection plate up to 90° C. simultaneously with the start of theinjection. The resultant cell was subjected to UV-ray irradiation (byusing one light source through one substrate) through the reflectingplate at the same light intensity as in Specific Example 5 at atemperature of 90° C. for 3 minutes continuously. The cell was thencooled to a temperature of 25° C., and subjected to the UV-rayirradiation for another 7 minutes. The cell was heated up to atemperature of 100° C., and annealed to 25° C. over 8 hours. Theretardation (Δn₁ ·d₁) of the thus manufactured liquid crystal cell was650 nm. A polarizing plate and a phase plate (Δn₂ ·d₂ =350 nm), e.g., aretardation film were attached to the cell in the relationship as shownin FIG. 8. Thus, a reflective type STN liquid crystal display deviceincluding one polarizing plate was produced. The display devicemanufactured in Specific Example 8 is a reflective type, which cannot beevaluated similarly to a transmissive type display device, and hence,the electro-optical characteristics of this display device are listednot in Table 4 but in Table 6 below.

                  TABLE 6                                                         ______________________________________                                        Reflectance (%):                                                              Comparative                                                                             Comparative Comparative                                                                             Specific                                      Example 9 Example 11  Example 12                                                                              Example 8                                     ______________________________________                                        100       68          65        165                                           ______________________________________                                    

note: The reflectance is indicated as a ratio to that of the device ofComparative Example 9, whose reflectance is taken as 100.

The reflectance of the devices of Comparative Examples 11 and 12 listedin Table 6 was measured when each device included the same type of areflecting plate as that used in Specific Example 8. As is understoodfrom Table 6, the device of Specific Example 8 is bright because itcontains only one polarizing plate. The reflectance was measured byusing a ratio of a reflectance of light entering at an angle of 30°against the normal line of the liquid crystal display device to areflectance of white light in the direction of the normal line. Theobservation of the thus manufactured liquid crystal display device foundthat the display was bright as compared with that of the devicemanufactured in Comparative Example 12 and that the brightness in thepolymeric wall was improved.

Comparative Example 13

Into the same type of cell manufactured in Specific Example 9 describedbelow, the liquid crystal material ZLI-4792 (manufactured by Merck &Co., Ltd.; wherein the twist angle was previously adjusted to be 90° byadding S-811) was injected, thereby manufacturing an ordinary TN liquidcrystal display device.

When the liquid crystal display device was pressed with a pen, thedisplay color was changed.

Specific Example 9 (A reflective type TN liquid crystal display device)

A pair of glass substrates each having a thickness of 1.1 mm and bearingstriped transparent electrodes (eight electrodes/mm; an interval of 2582 m) of ITO with a thickness of 2000 Å were coated with polyimide(AL4552; manufactured by Nippon Synthetic Chemical Industry, Co., Ltd.)by spin coating, and subjected to a rubbing treatment in one directionwith a nylon cloth. The resultant substrates were attached to each otherso that the alignment directions cross at 90° with a spacer having adiameter of 5 μm interposed therebetween, thereby manufacturing a cell.Then, 0.004 g of the compound C (polymerizable chiral agent), 0.10 g ofp-phenyl styrene, 0.85 g of the compound D, 0.046 g of 1,4-butanediolmethacrylate, 5 g of the liquid crystal material ZLI-4792 (manufacturedby Merck & Co., Ltd.; wherein the twist angle was previously adjusted tobe 90° by adding S-811) and 0.025 g of the photopolymerization initiatorIrgacure 651 were homogeneously mixed. The obtained mixture was injectedinto the cell by pillary injection. The thus manufactured cell wasirradiated with UV rays by using two high pressure mercury lampsemitting collimated light through the respective substrates in the samemanner as in Specific Example 5.

Polarizing plates were attached to the resultant cell so that thepolarization axes were matched with the rubbing direction, therebymanufacturing a transmissive type TN liquid crystal display device. Thetransmission of the liquid crystal display device under application ofno voltage is listed in Table 7 together with that of an ordinary TNliquid crystal display device manufactured in Comparative Example 13described above.

                  TABLE 7                                                         ______________________________________                                                      Specific                                                                             Comparative                                                            Example 9                                                                            Example 13                                               ______________________________________                                        Transmission (%)                                                                              93       97                                                   ______________________________________                                    

It is understood from Table 7 that although the display device ofSpecific Example 9 includes a polymeric wall, it is as excellent as theordinary display device including no polymeric wall in the transmission.Then, a reflecting plate was provided on the back face of each of thesedisplay devices, thereby manufacturing reflective type TN liquid crystaldisplay devices. These display devises were found to be equallyexcellent in the reflectance under application of no voltage. When thedisplay device of Specific Example 9 was pressed with a pen, the displaycolor was little changed, while the display color was changed inpressing the display device of Comparative Example 13.

In order to check the tight attachment between the polymeric wall andthe substrates, a portion in the shape of a square of 20 mm ×20 mmincluding the polymeric wall and the liquid crystal regions alone wascut out from the cell. The substrate attached to the polymeric wall waspulled, but could not be peeled off with ease. The same procedure wasperformed with regard to the cell of Comparative Example 13, but thesubstrate was peeled off while cutting the square portion.

Now, the characteristics and modification examples of the presentinvention will be described.

Display mode:

The present invention is applicable to various modes of liquid crystaldisplay devices such as transmissive or reflective type TN, STN, ECB,FCL, and any of these modes including a pigment. As an application notutilizing the alignment regulating force on a substrate, a liquidcrystal domain can be formed at random or radially. Further, the presentinvention is applicable to a display device achieving a wide viewingangle in which the liquid crystal molecules in each liquid crystalregion are aligned radially or concentrically. Although the presentinvention is applicable to both the reflective type and the transmissivetype, it is preferable to adopt the reflective type when used as aportable remote terminal because the reflective type requires no backlight and consumes less power.

Production method:

In the present invention, it is preferable that the alignment regulatingforce on a substrate is effectively used and that a polymeric wall isformed substantially in a non-pixel portion. For this purpose, a mixtureincluding liquid crystal, a photopolymerizable material (i.e.,photopolymerizable liquid crystal and a polymerizable compound) and aphotopolymerization initiator is injected between substrates that arepreviously subjected to an alignment treatment, and then, the resultantsubstrates are locally irradiated with UV rays so that the pixel issubstantially shielded. It is not necessary to add thephotopolymerization initiator to the mixture to be injected.

Through the UV-ray irradiation, the photopolymerizable material ispolymerized into a polymeric material to form a polymeric wall in aportion irradiated with UV rays. The polymeric material pushes theliquid crystal to a portion not irradiated with UV rays. As a result,the polymeric wall is formed in an irradiated portion, while the liquidcrystal region is formed in a portion not irradiated with UV rays. Inorder to effectively use the alignment regulating force on thesubstrate, a photopolymerizable material having liquid crystallinity isused as part or whole of the photopolymerizable material. Accordingly,the photopolymerization can be caused without spoiling the liquidcrystallinity of the mixture

Moreover, in order to attain more uniform alignment in the presentinvention, the mixture is injected between the substrates preferably ata temperature exceeding the isotropic temperature of the mixture, andthe photopolymerization is preferably caused as follows: the UV-rayirradiation is intentionally provided with a regular intensitydistribution to cause the photopolymerization in a regular pattern; andin order to allow the mixture to have liquid crystallinity, thetemperature of the substrates is decreased so as to attain the nematicor smectic phase, and then the photopolymerization is begun. At thispoint, the smectic phase excellent in liquid crystallinity is preferablyused because it is possible to remove the photopolymerizable materialfrom the liquid crystal region by using the smectic phase liquidcrystal.

Method for providing UV-ray intensity distribution:

In the present invention, how the UV-ray intensity distribution isprovided is significant. It is preferable to make the UV-ray intensitydistribution regular by using light intensity adjustment means such asthe above-mentioned photomask, microlens and interference plate.

When a photomask is used, the photomask can be placed either inside oroutside of the cell as far as it can cause a regular intensitydistribution of UV rays. In disposing the photomask outside of the cell;it is impossible to attain a desirable UV-ray intensity distributionwhen the distance between the photomask and the cell is large.Accordingly, the photomask is preferably disposed in the vicinity of themixture of the liquid crystal and the photopolymerizable material It isparticularly preferable that a substantial photomask for cutting UV raysis disposed inside the cell because the photomask is in contact with themixture in this case. Specific examples for providing the photomaskinside the cell include the following: In a reflective type liquidcrystal display device, only a portion of a reflecting platecorresponding to a pixel is allowed to have a reflecting function and aportion corresponding to a non-pixel portion is made transparent; inboth a reflective type and a transmissive type liquid crystal displaydevices, a film that transmits visible light but cuts UV rays, such as acolor filter and an organic polymer film, is formed on one of thesubstrates in a regular pattern in accordance with a desired intensitydistribution. Further, it is not necessary that the irradiated portionhas 100% intensity and the rest 0%. Therefore, it is possible to locallyadjust the transmitted amount of UV rays by using a material that can beused as a transparent electrode such as IT0. Also in this case, thephase-separation between the liquid crystal and the photopolymerizablematerial can be effectively caused.

According to the study by the present inventors, it is preferred to makea weakly irradiated area (described below) larger than a pixel so as toextremely decrease the interface between the liquid crystal region andthe polymeric wall within the pixel. Therefore, the light intensityadjustment means such as a photomask, which allows UV rays to irradiatethe nonpixel portion alone, is preferred for the following reason: Whenan area that is weakly irradiated because of the shield by a lightshielding portion of the photomask (weakly irradiated area) has a sizesmaller than 30% of that of a pixel, the size of the liquid crystalregion to be formed is also smaller than 30% of that of the pixel. As aresult, the interface between the liquid crystal region and thepolymeric wall is too large in a pixel, thereby causing light scatteringwhich largely decreases the contrast.

The weakly irradiated area can take any shape as far as it covers 30% ormore of the area of a pixel so as to locally decrease the UV-rayintensity. Therefore, unlimited examples of the shape include a circle,a square, a trapezoid, a rectangular, a hexagon, a rhombus, the shape ofa letter, a figure partitioned with a curve or a line, part of theseshapes, a combination of these shapes, and a collection of these shapeseach small in size. In practicing the present invention, one or more ofthese shapes is selected, but it is preferred to adopt merely one kindof shape in order to increase the uniformity of a liquid crystaldroplet.

In the present invention, it is significant to align the liquid crystalregions regularly horizontally in accordance with the alignment of thepixels. Therefore, the location of the weakly irradiated area isimportant. It is preferred that the weakly irradiated areas are locatedin accordance with the pitch of the pixels so that one weakly irradiatedarea be provided in each pixel. It is possible to provide one weaklyirradiated area to several pixels, and for example, each line of pixelsor a group of several pixels can be provided with one weakly irradiatedarea. Moreover, the weakly irradiated areas are not necessary to beindependent from one another and can be connected with one another atthe ends thereof as far as an area for cutting UV rays most effectivelyhas one of the above-mentioned shapes and aligned in the above-mentionedmanner. When a pixel is large, it is possible to intentionally form apolymeric wall within a pixel. In this case, although the contrast isdecreased, the supporting force against an external pressure isenhanced.

In addition, it is preferred to use a UV-ray source emitting light ascollimated as possible. When the light is not collimated, UV rays enternon-irradiated areas to cause the photopolymerization of thepolymerizable material within a pixel, thereby decreasing the contrast.When a photomask or the like is provided within the cell so as to besubstantially in contact with the mixture of the liquid crystal and thephotopolymerizable material, however, the light can be less collimated.

Roughness in the display:

In a conventional polymer dispersed liquid crystal display device, lightscattering is caused on the interface between the liquid crystal regionand the polymeric wall due to the difference in the refractive indextherebetween. This light scattering is also caused in a non-scatteringtype liquid crystal display device, which includes large liquid crystalregions and requires a polarizing plate for the display. The lightscattering causes a problem of roughness in the display. In the presentinvention, however, even the polymerizable material is partly in thesame alignment state as the liquid crystalline state before and afterthe polymerization, and the liquid crystal and the photopolymerizablematerial or the photopolymerizable liquid crystal have approximately thesame refractive index, resulting in decreasing the roughness in thedisplay. For this purpose, it is preferable that the opticalcharacteristics such as Δn, n_(e), n_(o) and the chiral pitch of theliquid crystal in the liquid crystal region are matched with those ofthe polymerizable material as well as possible.

Photopolymerizable liquid crystal:

In the present invention, polymerization is caused in a homogeneousmixture of a liquid crystal and a photopolymerizable material(polymerizable material having liquid crystallinity) to polymerize thephotopolymerizable material in the liquid crystalline state between twosubstrates having been subjected to an alignment treatment, therebycausing phase-separation between the liquid crystal and the polymericmaterial. Accordingly, it is possible to form a polymeric wall on whichthe photopolymerizable liquid crystal is fixed, and hence, the polymericwall can attain a similar alignment regulating force to that on thesubstrate. This results in that the liquid crystal molecules receive thealignment regulating force not only from the surface of the substratebut also from the surface of the polymeric wall. Therefore, thealignment of the liquid crystal molecules is stabilized, and inaddition, the alignment of the liquid crystal molecules in the vicinityof the polymeric wall can be uniform. In the conventional method inwhich a polymeric wall is previously formed (disclosed in JapaneseLaid-Open Patent Publication No. 61-502128 and the like), the alignmentof the liquid crystal molecules in the vicinity of the polymeric wall isdisordered, resulting in a difficulty in obtaining uniform display.

In this conventional method, uniform display cannot be obtained asdescribed above. In addition, since the optical characteristics such asΔn, n_(e), n_(o) and the chiral pitch of the liquid crystal in theliquid crystal region are different from those of the polymericmaterial, the transmission under application of no voltage is decreasedin the polymeric wall. Therefore, when such a device is used as areflective type liquid crystal display device, the display is generallydark.

The photopolymerizable liquid crystal used in the present inventionincludes a polymerizable functional group in its molecule, and anexample includes a compound represented by the following Formula 5:

    A-B-LC.sub.1

or

    A-B-LC.sub.2 -B-A                                          Formula 5

wherein A indicates a polymerizable functional group having anunsaturated bond or having a heterocyclic ring structure with distortionsuch as epoxy such as CH₂ =CH--, CH₂ =CH--COO--, CH₂ =CH--COO--,##STR5## and --N=C=O; B indicates a coupling group for connecting thepolymerizable functional group with a liquid crystalline compound suchas an alkyl chain (--(CH₂)n--), an ester bond (--COO--), an ether bond(--O--), a polyethylene glycol chain (--CH₂ CH₂ O--) and a combinationthereof; and LC₁ indicates a liquid crystalline compound such as acompound represented by the following Formula 6, a cholesterol ring orits derivatives:

    D-E-G                                                      Formula 6

wherein G indicates a polar group for allowing the dielectric constantanisotropy and the like of the liquid crystal to be exhibited such as abenzene ring, a cyclohexane ring, a paradiphenyl ring, aphenylcyclohexane ring, a terphenyl ring and a diphenylcyclohexane ringhaving a functional group such as --CN, --OCH₃, --F, --Cl, --OCF₃,--OCC1₃ ; E indicates a functional group for connecting D with G such as--CH₂ --, --CH₂ CH₂ --, --O--, --C.tbd.C--, --CH=CH--; and D indicates afunctional group to be connected with B in Formula 5 such as aparaphenyl ring, a 1,10-diphenyl ring, a 1,4-cyclohexane ring and a1,10-phenylcyclohexane ring. LC₂ in Formula 5 includes a rigid groupsuch as a paraphenyl ring, a 1,10-diphenyl ring, a 1,4-cyclohexane ringand a 1, 10-phenylcyclohexane ring. Such a functional group can be usedsingly, or a plurality of them can be bonded with each other with acoupling group such as --CH₂ CH₂ --, --CH=CH--, --C.tbd.C--, --COO--,--N=CH--, --O--, --N=N--and --COS--. The group indicated by D affectsthe dielectric constant anisotropy and the refractive index anisotropyof the liquid crystal molecules.

When the dielectric constant anisotropy of the liquid crystal used inthe present liquid crystal display device is positive, the polar groupindicated by G in Formula 6 is positioned so as to make the dielectricconstant anisotropy Δε negative. Specifically, LC₁ includes2-substitution product, 3-substitution product, 2,3-substitution productand the like of the benzene ring in the polar group G. When thedielectric constant anisotropy of the liquid crystal is negative, thepolar group G is positioned so as to make the dielectric constantanisotropy Δε positive. Specifically, LC₁ includes 4-substitutionproduct, 3,4,5 -substitution product, 3,4-substitution product and thelike of the benzene ring in the group G. When the number of thesubstituent in the substitution product of the polar group is plural inone molecule, all the substituents are not required to be of the samekind. In both the cases where the dielectric constant anisotropy Δε ispositive and it is negative, it is not necessary to use only one kind ofpolymerizable liquid crystal. Therefore, plural kinds of thepolymerizable liquid crystal can be used together as far as at least oneof the above-mentioned compounds is included.

Chiral agent:

In order to allow the polymeric wall to have a chiral pitch as in theliquid crystal region, the material for forming the polymeric wall,i.e., the photopolymerizable material, is required to include a materialhaving an optical rotary power. Such a material is a compound includingan optically inactive asymmetric carbon atom in its molecule and havingthe polymerizable portion described above with regard to thephotopolymerizable liquid crystal. Further, it is preferable that thematerial has a rigid structure in the shape of a lot similarly to thephotopolymerizable liquid crystal in order not to spoil the liquidcrystallinity. The amount of the polymerizable chiral agent to be addedto the mixture of the liquid crystal and the photopolymerizable materialdepends upon the kind of the photopolymerizable materials to be usedtogether and the kind of photopolymerizable chiral agent. Therefore, theamount is not specified in the present invention. It is preferable,however, that the chiral agent is added so that the chiral pitch thereofbe matched with the chiral pitch of the liquid crystal molecules in theliquid crystal region as well as possible.

Polymerizable material:

Examples of the photopolymerizable material to be polymerized throughlight irradiation include acrylic acid and acrylate having a long chainalkyl group with 3 or more carbon atoms or a benzene ring, such asisobutyl acrylate, stearyl acrylate, lauryl acrylate, isoamyl acrylate,n-butyl methacrylate, n-lauryl methacrylate, tridecyl methacrylate,2-ethylhexyl acrylate, n-stearyl methacrylate, cyclohexyl methacrylate,benzyl methacrylate, 2-phenoxyethyl methacrylate, isobornyl acrylate,and isobornyl methacrylate. Further, in order to increase the physicalstrength of the polymeric wall, the following multi-functional compoundhaving two or more functional groups can be used: R-684 (manufactured byNippon Kayaku Co., Ltd.), bisphenol A dimethacrylate, bisphenol Adiacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanedioldimethacrylate, trimethylol propane trimethacrylate, trimethylol propanetriacrylate, tetramethylol methane tetraacrylate, and neopentyldiacrylate. More preferably, a halogenated photopolymerizable compound,particularly, a chlorinated or fluorinated compound as follows can beused: 2,2,3,4,4,4-hexafluorobutyl methacrylate,2,2,3,4,4,4-hexachlorobutyl methacrylate, 2,2,3,3-tetrafluoropropylmethacrylate, 2,2,3,3-tetrachloropropyl methacrylate,perfluorooctylethyl methacrylate, perchlorooctylethyl methacrylate,perfluorooctylethyl acrylate, and perchlorooctylethyl acrylate.

In the present invention, a polymeric wall is formed in a cell so as toprevent the variation of the cell thickness due to external pressure.Therefore, the glass transition temperature (Tg) is a significant factorin selecting the photopolymerizable material. When the glass transitiontemperature is lower than room temperature, the material is in the statelike rubber at room temperature, and hence is transformed with ease byan external pressure. Therefore, such a material is not suitable to thepresent invention. The glass transition temperature of thephotopolymerizable material to be used is preferably 0° C. or more, andmore preferably 40° C. or more.

Polymerization inhibitor:

In order to form the liquid crystal region in accordance with thepattern of the used photomask, the rate of the polymerization ispreferably low. When the polymerization rate is high, the polymerizationis sufficiently caused in an area shielded by the photomask due to thelight scattering and reflective on the substrate, thereby allowing thepolymerizable material to be attached to the pixel. This results in theformation of the polymeric wall in the pixel. Specific examples of thepolymerization inhibitor include styrene, the derivatives of styrenesuch as pfluorostyrene and paraphenylstyrene, and nitrobenzene.

Liquid crystal material:

The liquid crystal is not specified in the present invention because theoptimal liquid crystal largely depends upon the display mode. Forexample, in the TN, STN and ECB modes, examples of the preferablematerial include an organic mixture exhibiting a liquid crystallinestate around room temperature such as nematic liquid crystal (includingliquid crystal for dual frequency drive; including liquid crystal havinga dielectric constant anisotropy Δε<0) and nematic liquid crystalincluding cholesteric liquid crystal in terms of the characteristicsthereof. More preferably, liquid crystal excellent in chemical reactionresistance is used because of the photopolymerization effected duringthe processing. Specific examples of such liquid crystals include thosehaving a functional group such as a fluorine atom, for example,ZLI-4801-000, ZLI-4801-001, ZLI-4792 and ZLI-4427 (all manufactured byMerck & Co., Inc.). In selecting liquid crystal and a liquid crystallinecompound having a polymerizable functional group in its molecule, it ispreferred, from the viewpoint of miscibility, that the materials to beselected have similar portions for exhibiting the liquid crystallinecharacteristics. Particularly, when a fluoric or chloric liquid crystal,which has specific chemical characteristics, is used, it is preferredthat the polymerizable liquid crystal to be used together is also afluoric or chloric compound.

The refractive index of the liquid crystal is preferably | (n_(e) orn_(o))-n_(p) |<0.1, wherein n_(p) indicates the refractive index of thepolymeric material to be used together. The refractive index out of theaforementioned range causes mismatching in the refractive index, therebyincreasing the roughness in the display. More preferably, n_(p) takes avalue between n_(e) and n_(o). When the refractive index of the liquidcrystal is within this range, there is only a small difference in therefractive index between the polymeric wall and the liquid crystalregion even under application of a voltage. Therefore, light scatteringon the interface between the liquid crystal region and the polymericwall is extremely decreased. In particular, the reflective index of theliquid crystal equal to n_(o) is preferable because the black levelunder application of a voltage is improved.

Mixed ratio of the materials:

It is necessary to add the photopolymerizable material (including thepolymerizable chiral agent) in such an amount that the mixture of theliquid crystal, the photopolymerization initiator and thephotopolymerizable material can be in the liquid crystalline state. Theamount to be added is not specified in this invention because the amountfor exhibiting the liquid crystallinity depends upon the kind ofmaterials. Preferably, the photopolymerizable liquid crystal is added tothe photopolymerizable material by 30 wt % or more and 90 wt % or less.When the proportion of the photopolymerizable liquid crystal is below 30wt%, a temperature range in which the mixture is in the liquidcrystalline state becomes small, and hence it is impossible tosufficiently align the STN liquid crystal between the substrates. Whenthe proportion exceeds 90 wt %, the elastic modulus of thephotopolymeric material after the polymerization is too low to obtainsufficient strength for supporting the cell.

The weight ratio of the liquid crystal to the photopolymerizablematerial is preferably 50:50 through 97:3, and more preferably 70:30through 90:10. When the proportion of the liquid crystal is below 50 wt%, the interaction between the polymeric wall and the liquid crystal isincreased, and therefore, an extremely high voltage is required to drivethe cell. Further, the size of the liquid crystal regions aligned inaccordance with the alignment regulating force on the substrate isdecreased. Thus, the resulting display device is not suitable forpractical use. When the proportion of the liquid crystal exceeds 97 wt%, the physical strength of the polymeric wall is decreased, resultingin unstable performance of the display device.

Retardation (d·Δn):

Since the alignment of the liquid crystal region in the present liquidcrystal display device is similar to that in an ordinary STN liquidcrystal display device, the optimal retardation and the retardation ofthe phase plate are the same as those in the ordinary STN liquid crystaldisplay device.

In a reflective type display device, the product (d₁ ·Δn₁) of a cellthickness d₁ and Δn₁ of the liquid crystal is preferably in the rangebetween 500 nm and 800 nm in terms of the contrast and coloring. Adisplay device for colored display alone, however, can be changed into adevice for black and white display by providing a substrate having aretardation film in a manner shown in FIG. 8. For this purpose, theproduct (d₂ ·Δn₂) of the refractive index anisotropy Δn₂ of thesubstrate having the retardation film and the cell thickness d₂ isextremely significant, and is preferably in the range between 150 nm and380 nm. In addition, (d₁ ·Δn₁ -d₂ ·Δn₂) is preferably in the rangebetween 450 nm and 550 nm. Further, the optical axis of the substratehaving the retardation film and the alignment direction of the liquidcrystal on the substrate are also significant. As shown in FIG. 8, whenan angle between the alignment direction (rubbing direction) n of theliquid crystal on the upper electrode substrate (corresponding to thesubstrate 7 in FIG. 4) and the optical axis o of a phase plate, e.g., aretardation film (corresponding to the phase plate 13 in FIG. 4) istaken as an angle β, and the twist angle of the liquid crystal is takenas an angle θ (=240°), it is preferable that the relationship β=(θ-180)/2±10° is satisfied. Further, an angle a between the alignmentdirection n of the liquid crystal on the upper substrate and thepolarization axis m of the polarizing plate is preferably 30±10°.Further, the twist angle θ0 is an angle between the alignment directionn of the liquid crystal in the vicinity of the upper electrode substrateand the alignment direction 1 of the liquid crystal in the vicinity ofthe other substrate having a reflecting function, and is preferably inthe range between 220° and 290°. This range is also applicable to atransmissive type display device described below.

FIG. 24 shows a preferable alignment direction of the liquid crystal andthe like in a transmissive type display device including two polarizingplates sandwiching a cell. In FIG. 24, the alignment direction of theliquid crystal in the vicinity of the lower substrate is indicated as t,the alignment direction of the liquid crystal in the vicinity of theupper substrate is indicated as u, the polarization axis of the upperpolarizing plate is indicated as v and the polarization axis of thelower polarizing plate is indicated as w. The relationship among theangles shown in FIG. 24 is merely an unlimited example in a transmissivetype display device.

Photocolymerization initiator:

A photopolymerization initiator is not always required to be added tothe mixture to be injected into a cell, but is preferably added theretoin order to effect the polymerization of the photopolymerizable materialsmoothly. Specific examples of the photopolymerization initiator (or acatalyst) includes Irgacure 184, Irgacure 651, Irgacure 907, Darocure1173, Darocure 1116 and Darocure 2959. The amount of the polymerizationinitiator to be added is preferably 0.3%, or more and 5% or less of theentire mixture including liquid crystal and a polymerizable material forthe following reason: When the mixed ratio is below 0.3%, thephotopolymerization reaction cannot be sufficiently carried out. Whenthe mixed ratio exceeds 5%, the rate of the phase-separation between theliquid crystal and the polymeric material is too fast to be controlled,and the thus formed liquid crystal region is so small that a higherdriving voltage is required.

When a plastic substrate is used, UV rays are absorbed by the substrate,and hence the polymerization is difficult to carry out. Therefore, insuch a case, it is preferred to use a photopolymerization initiator thatabsorbs visible light and can be polymerized by visible light. Specificexamples of such a polymerization initiator include Lucrin TPO(manufactured by BASF), KYACURE DETX-S (manufactured by Nippon KayakuCo., Ltd.) and CGI369 (manufactured by Ciba-Geigy Corporation).

Driving method:

The driving method applicable to the present invention is not specifiedbut includes a simple matrix drive and an active matrix drive usingTFTs, MIMs, and the like. With regard to an STN liquid crystal displaydevice, however, the simple matrix drive is preferable in terms of thecharacteristics thereof.

Material for substrate:

As a material for a substrate, glass and a polymer film, which areexamples of transparent solid, and an Si substrate, which is an exampleof opaque solid can be used. Further, for a reflective type displaydevice, a substrate bearing a metal film can be also used.

As a plastic substrate, a preferable material that does not absorbvisible light such as PET, an acrylic polymer, styrene or polycarbonatemay be used.

Further, it is possible to use two different kinds of substratesselected from among the above examples can be used to form a cell. It isalso possible to combine substrates having different thicknesses whetheror not they are the same kind.

Input/output device:

In the present invention, it is possible to combine the aforementionedliquid crystal display device with an input/output device of a pressuresensitive system, an electrostatic induction system or anelectromagnetic induction system. These systems will be described.

(1) Pressure sensitive system:

In this system, a transparent plastic sheet having uniform surfaceresistance is overlapped on glass with a small distance therebetween.Since the present liquid crystal display device has a resistance againstexternal pressure, it is possible to use two thin plastic sheets,resulting in a thin input portion. Therefore, the thus produced liquidcrystal display input/output device has a small parallax and can beeasily operated.

(2) Electrostatic induction system:

In this system, the position of a point pressed with a pen is detected,as is shown in FIG. 13B, by using an electrostatic coupling between theelectrode of a tablet panel 90, which is applied with a voltage for thedetection, and the electrode at the tip of an entry pen 93. Also in thissystem, input is conducted through the upper surface of the liquidcrystal display device, and hence an external pressure is applied to theliquid crystal display device. When the present liquid crystal displaydevice is used as a liquid crystal display device 91, a protection panelor the like is not required to be disposed between the tablet panel 90and the liquid crystal display device 91 of FIG. 13B because the presentdevice has a sufficient resistance against an external pressure.

When the present liquid crystal display device is applied to a displayintegrated tablet 92, i.e., a liquid crystal display panel with afunction of detecting pen position, as shown in FIG. 13C, in which theelectrodes in the liquid crystal display panel are used for the displayand the input by a timesharing system (reported in Sharp TechnicalJournal, No. 56, pp. 15-18), the liquid crystal display panel does notrequire a protection panel or the like for relaxing an externalpressure. This results in a light and thin liquid crystal display panel.

The detailed descriptions of the input/output device can be found inJapanese Laid-Open Patent Publications Nos. 56-77884 and 5-53729. Thesedocuments are cited by the present application.

(3) Electromagnetic induction system:

In this system, an AC field generated by a coil in an entry pen isapplied to a loop circuit for detecting a coordinate formed on a tabletpanel, thereby determining the coordinate based on the position of aloop inducted by the voltage. In this system, the tablet can bepositioned below a liquid crystal display panel, and hence a pallarax ishardly caused in the display of the liquid crystal display device. Inthe conventional liquid crystal display panel, however, a protectionpanel is required. The present liquid crystal display device hassufficient resistance against external pressure, and therefore, it isnot necessary to provide a protection panel or the like for relaxing theexternal pressure.

As is described in detail above, in the present liquid crystal displaydevice, which can adopt various conventionally used liquid crystaldisplay modes such as TN, STN, FLC and a wide viewing angle mode, thepolymeric wall constituting the display medium is tightly attached tothe substrates. As a result, it is possible to prevent the cellthickness from being varied by an external pressure. Moreover, thisliquid crystal display device is applicable to pen entry operationwithout using a protection film or the like. Therefore, it is possibleto avoid a pallarax between the display and a pointed position due tothe thickness of the protection film. Further, when a film substrate isused to form a cell, it is possible to provide a light STN liquidcrystal display device in which the display quality is little varied byan external force and which is hardly damaged or transformed by anexternal force.

In addition, the electro-optical characteristics of the present liquidcrystal display device rises sharply, and hence it is possible to attaina sufficient duty ratio. Accordingly, there is no need to use a TFT,resulting in decreasing the production cost.

The present liquid crystal display device can be used as a displaysuitable to a pen detective keyboard for a portable remote terminal,which is small in weight and consumes little power.

Various other modifications will be apparent to and can be readily madeby those skilled in the art without departing from the scope and spiritof this invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the description as set forthherein, but rather that the claims be broadly construed.

What is claimed is:
 1. A liquid crystal display input/output devicecomprising:a liquid crystal display device including a plurality ofpixels and polymeric walls formed in a pattern between a pair ofelectrode substrates and liquid crystal regions at each pixel beingsurrounded by the polymeric walls and input means for detecting aposition of a desired point by touching the desired point.
 2. A liquidcrystal display input/output device according to claim 1, wherein aplurality of liquid crystal domains are formed in a pixel, each of theliquid crystal domains including at least two areas having differentalignment directions from each other.
 3. A liquid crystal displayinput/output device according to claim 1, wherein the liquid crystaldisplay device is one of a TN mode, an STN mode and an FLC mode.
 4. Aliquid crystal display input/output device according to claim 1, whereinthe polymeric wall are tightly attached to the electrode substrates. 5.A liquid crystal display input/output device according to claim 1,wherein electrodes on the electrode substrates in the liquid crystaldisplay device work as an input detection electrode in a liquid crystaldisplay integrated tablet.
 6. A liquid crystal display input/outputdevice according to claim 1, wherein the input means adopts one of anelectromagnetic induction system, an electrostatic induction system anda pressure sensitive system.
 7. A liquid crystal display deviceaccording to claim 1, wherein said polymeric walls are formed of a curedphotopolymerizable material which has been separated from a mixtureincluding liquid crystal and a photopolymerizable material.